Arrows include an arrow shaft having an arrow point attached to one end of the shaft and a nock, adapted to be received by a bow string, attached to the other end of the shaft. Arrow shafts may be fabricated from a wide variety of materials, including wood, metal such as aluminum, carbon, fiberglass, composites such as aluminum/carbon, and the like. Wood shafts are typically of a solid, substantially cylindrical construction, whereas shafts made from other materials are typically of a hollow, tubular construction.
Various approaches have been developed for attaching an arrow point to the hollow end portion of a tubular arrow shaft. In some approaches the arrow point is attached directly to the arrow shaft, and in other approaches the arrow point is attached to the arrow shaft indirectly through an adapter. Most arrows sold commercially today use the adapter approach for mounting arrow points.
One widely used type of adapter is designed to be inserted and glued into a hollow end portion of a tubular arrow shaft. This kind of adapter includes a bore for receiving the corresponding mounting portion of an arrow point. The body of such adapters may be provided with glue grooves in order to enhance bonding between the adapter and the arrow shaft. Examples of this class of adapter and corresponding arrow points are described in U.S. Pat. Nos. 4,943,067; 4,671,517; and 4,533,146. Such an adapter and corresponding arrow points are also described in the AMO Interchangeable Point System Standard. Some commercial embodiments of these adapters include glue grooves to receive glue used to bond the adapter in place.
When an adapter is inserted and glued into the hollow end portion of an arrow shaft, it is important that the glue bond be strong enough to hold the adapter in place and in proper alignment during shotmaking activities. For example, when an arrow impacts a target, is pulled from a target, or the like, it would be undesirable for the adapter to come loose or jar out of alignment. One factor affecting such bond strength is the amount of surface area of the adapter which is available for bonding engagement with the arrow shaft. In order to ensure adequate bond strength between a conventional adapter and an arrow shaft, a relatively large surface area of the conventional adapter is required for adequate bonding.
It is also important that the adapter be as lightweight as possible, while still maintaining sufficient structural strength to withstand impact and tugging forces experienced by the arrow during shotmaking activities. Various approaches have been proposed for reducing the weight of an adapter. In some instances, lightweight polymer materials have been substituted for the aluminum most commonly used to make such adapters. Although lighter in weight, not all of such polymer materials are as strong as aluminum. As a result, adapters made from such materials tend to fail more easily and/or more often than aluminum adapters. Additionally, the desirable physical strength properties of an initially acceptable polymer material may tend to degrade over time. As a result, adapters made from such materials have a shorter service life than aluminum adapters. Further, even in those instances in which polymer materials provide an acceptable level of performance, polymeric adapters tend to be disfavored by the buying public.
Accordingly, there remains a need for an approach which provides adapters with reduced weight, while still maintaining adequate strength and bonding characteristics.